Mapping, cloning, and functional characterization of CsPBGD in leaf necrosis and its potential role in disease resistance in cucumber (Cucumis sativus L.)

文献类型： 外文期刊

第一作者： Liu, Mengying

作者： Liu, Mengying;Jin, Zhuoshuai;Chen, Kang;Gao, Weizhi;Wang, Mengdan;Li, Yuhong;Wang, Yixin;Chen, Peng;Yue, Hongzhong

作者机构：

期刊名称：THEORETICAL AND APPLIED GENETICS （ 影响因子：4.2； 五年影响因子：4.9 ）

ISSN： 0040-5752

年卷期： 2025 年 138 卷 7 期

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收录情况： SCI

摘要： Key messageMap-based cloning revealed that the mutation in a highly conserved amino acid of the CsPBGD, which encodes porphobilinogen deaminase, causes the phenotype of leaf necrosis and enhanced resistance to powdery mildew and gray mold in cucumber.AbstractLesion mimic mutants (LMMs) are valuable genetic resources for studying programmed cell death (PCD) and disease resistance. Although a number of genes controlling lesion mimic have been identified in model species, none have been mapped or cloned in cucumber. Here, we identified two cucumber mutants, C1173 and C2123, which exhibit leaf necrosis due to PCD. Genetic analysis revealed that these phenotypes are controlled by two semi-dominant loci, ln1 and ln2, respectively. Both mutants were heterozygous, as homozygous dominants were lethal (one caused cotyledon etiolation lethality; the other was unobtainable). Fine mapping placed the ln1 locus within a 54.1 kb region on chromosome 3. Further investigation revealed ln1 and ln2 were allelic mutations, with CsPBGD (CsaV3_3G031800), encoding porphobilinogen deaminase, identified as the candidate gene for both mutants. Mutations in CsPBGD resulted in amino acid substitutions, Ala314Val in ln1 and Arg197Lys in ln2, disrupting enzyme activity and altering H2O2 accumulation. CsPBGD expression was significantly reduced in various organs of ln1. VIGS of CsPBGD in both cucumber and tobacco successfully displayed the leaf necrosis phenotype. CsPBGD proteins from both mutants and wild type (WT) were localized in chloroplasts. The mutants exhibited significantly enhanced resistance to powdery mildew (Podosphaera xanthii) and gray mold disease (Botrytis cinerea). Further studies showed that CsPBGD expression in the mutant was significantly more downregulated than in WT after P. xanthii infection, alongside increased H2O2 accumulation. This study is the first to characterize and clone CsPBGD in cucumber, revealing its involvement in resistance to disease.

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